DISCHARGE PATTERNS OF MOTONEURONS

运动神经元的放电模式

• 批准号: 2504327
• 负责人: PEDRO N RUDOMIN
• 金额: $ 9.33万
• 依托单位: NATIONAL POLYTECHNIC INSTITUTE
• 依托单位国家: 美国
• 财政年份: 1990
• 资助国家: 美国
• 起止时间: 1990-12-01 至 2000-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2504327
• 关键词: afferent nerve; cats; dorsal column; dorsal horn; dorsal motor nucleus; gamma aminobutyrate; interneurons; motor neurons; neural information processing; neuroanatomy; neuromuscular transmission; synapses

DESCRIPTION (Applicant's abstract): The long term goal of this research has been to characterize the neuronal circuitry involved in the presynaptic control of the synaptic effectiveness of primary afferents in the mammalian spinal cord and to disclose the role played by presynaptic inhibition in sensory-motor integration. Most of the effort made during the next grant period will be addressed to document, in the anesthetized or decerebrated cat, the selectivity of the control exerted by segmental and supraspinal inputs on the pathways mediating primary afferent depolarization (PAD) of muscle and cutaneous afferents. The working hypothesis is that the intraspinal branches of afferent fibers are not obliged routes for information transmission but represent potential routes that can be used to direct the information flow to different sets of neurons according to the function to be performed. To this end, the effects of sensory and descending inputs on the pathways leading to PAD of two collaterals of individual Ia, Ib or cutaneous fibers, one collateral ending within the intermediate nucleus or dorsal horn at the L6 segmental level, and the other collateral ascending to Clarke s columns at the L3 level or to the dorsal column nuclei, respectively, will be compared. PAD will be inferred from changes in the intraspinal threshold of each collateral. Differences in the magnitude of the effects will be attributed to selectivity in the action exerted by the stimulated pathways on both collaterals. The effects of reversible spinalization on the resting PAD and on the PAD evoked by sensory and descending stimuli in segmental (L6) and ascending (L3) collaterals of the same muscle or cutaneous afferent will also be examined, as well as the inhibition of the resting and evoked PAD in Ia fibers following conditioning stimulation of cutaneous and joint nerves. Previous investigations have indicated that stimulation of the reticular formation produces PAD in a substantial number of afferent fibers reconnected with muscle spindles 1-3 months after a peripheral nerve crush. These effects have been attributed to a reorganization of the spinal pathways mediating PAD of the damaged fibers. Experiments proposed here are designed to examine i) if the PAD produced in afferents reconnected with muscle spindles is associated with presynaptic inhibition ii) the GABAergic nature of the PAD and of the presynaptic inhibition produced in the reconnected afferents iii) the extent to which the PAD produced by stimulation of the bulbar reticular formation is restricted to the damaged afferents and iv) possible changes in the effects produced by other descending inputs (cerebral cortex, raphe nuclei and red nucleus). A third project aims to examine the functional relationship between populations of dorsal horn neurons and intermediate nucleus interneurons mediating non-reciprocal postsynaptic inhibition (class I) or PAD (class II). Computational techniques will be used to disclose a) the spinal potentials which appear in synchrony with the spontaneous activity of class I or class II interneurons, b) the instraspinal location of the corresponding cord potentials, c) the changes produced when the extracellular field potentials and interneuronal activity evoked by stimulation of muscle and cutaneous afferents and by descending (reticulo-spinal and cortico-spinal) inputs is preceded by cord potentials associated with the activity of class I or class II interneurons. These issues are relevant for the understanding of the functional relationships between defined sets of spinal interneurons and their possible role in the modulation of information conveyed by afferent fibers.

描述（申请人的摘要）：这项研究的长期目标 表征与突触前的神经元电路 控制哺乳动物中主要传入的突触有效性 脊髓并披露突触前抑制作用的作用 感觉运动的整合。 在下一个赠款中所做的大部分努力 期间将在麻醉或杂交中进行记录 CAT，由节段和脊柱上施加的控制的选择性 介导初级传入去极化（PAD）的途径上的输入 肌肉和皮肤传入。 工作假设是 传入纤维的载体内分支不是义务的路线 信息传输，但表示可以用来用于的潜在路线 根据该信息流将信息流到不同的神经元集中 要执行的功能。 为此，感觉和 在通往两个侧边的路径上下降的输入 单个IA，IB或皮肤纤维，一个侧支结尾 L6节段的中间核或背角，另一个 在L3水平或背侧的Clarke S列上升到Clarke的列 将分别比较柱核。 垫子将从 每个侧支的脊柱内阈值的变化。 差异 效果的大小将归因于动作中的选择性 受刺激的途径在两个侧支上施加。 效果 在静止垫上和垫子上触发的脊柱脊柱可逆 并在节段（L6）和上升（L3）侧支中降低刺激 还将检查相同的肌肉或皮肤传入 调节后，抑制IA纤维中的静息和诱发垫 刺激皮肤和关节神经。 先前的研究表明，刺激网状 地层产生大量传入纤维的垫子 周围神经压伤后1-3个月与肌肉纺锤体重新连接。 这些作用归因于脊柱的重组 介导受损纤维垫的途径。 这里提出的实验是 设计用于检查i）是否与 肌肉纺锤体与突触前抑制有关ii）GABA能 垫的性质和突触前抑制的性质 重新连接的传统iii）垫子产生的程度 刺激鳞茎网状形成仅限于受损 传统和iv）其他其他效果可能改变 下降输入（脑皮质，raphe核和红色核）。 第三个项目旨在研究 背角神经元和中间核中间神经元的种群 介导非珠宝后突触后抑制（I类）或PAD（类 ii）。 计算技术将用于披露a）脊柱 与班级自发活动同步的电势 I或II类中间神经元，b） 相应的绳电位，c）当 细胞外场电势和神经元活动引起的 刺激肌肉和皮肤传入，并下降 （网状脊柱和皮质脊柱）输入之前是绳索电势 与I类或II类中间神经元的活动相关。 这些 问题与理解功能关系有关 在定义的脊柱中间神经元及其在 传入纤维传达的信息调节。